SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9438df0b0014401352ff57664a5fe61475f28dc021edfed01bb918ee1b24093' 
  AND token = 'HkcFAGIqSejQjWG8bdyl044RPrqApb8EWNtuf3bpYX4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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