SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec3335a427ed732347de726107c3fa1987ff641ca379ec2763cc3e309756d12f' 
  AND token = '6NTs6XA8ABjPCP3fOrsQCOenq+iFIMsrFlY7k7ThZbw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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