SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d38e1a27a37172d90ceafd8cca562486f56cd4939c36cdabc96f5cd55c1a2d3' 
  AND token = '9hQ3tOBozpltQvkK3FJkaSzUNYOzToPoWrViY9ZRiYk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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