SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6902cdf69119a18b6fa6a557f3fde374a985c5ca7d764d88a07697cb7f41144' 
  AND token = 'MNpomyx0qGlaKFDudSmM58xCNSeIoPHC714OkMk2qSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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