SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6e04b7a4628f7b3f5a28641b5a2c966eb164e10cdf6d2efa8336262d1ff7cd2' 
  AND token = '1rx0vFls+gjtdTzWQPYFpY6lSVTcL/xVKKDq8ZSE978=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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