SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd39785c2f02306667e2eb7439c77a2ff21364b2f4a2ca5a96be043f60acf43e2' 
  AND token = 'AEDlc29qZfKWQnfpPH+cfh9R2dsb6qDw8AR80NyXAG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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