SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b5b850b2f52d465ede32455535c3842980e87dbd657fe0d25f3aeec7940c1f9' 
  AND token = 'FMlMpDF0KnwCSdDYcXC/Phe2XIs38zZLavFNdqY3jKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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