SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7cd508a44c91c86639d2a3bad7318de9fecd37addac8b50076123279945211b' 
  AND token = '54rHO+KyeuVoL7w5RR+vCraymqCP1dosr+oB9qSHcHE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00011

JSON explain

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