SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c688ecb634c1784c8f02ec6a560d12570d1497537110529c0ca81b1ba588638a' 
  AND token = 'AvsOZ8e0bkhwRb1pYp2HvihiGWR5fy9ViwRgm3xg9bA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}