SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b51183e29b460ba6b01206b76a85b942eb7391f23ef88f3024c91fa60a7cc78c' 
  AND token = 'iP2H5yXLfKh7pLNgtAJMjRumQcfB/FZNV5qHKMQz2cA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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