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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20e0049c0c31483dd08f03b0a1c453aa5e51d17ddab2ce0f7e80ad8d04ced503' 
  AND token = 'ZN5lPX9SZQuAMs9X6efGy+PQw2tbo3+nNBi/2rJPYZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}