SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fb16b19a8c80fa5ba028b66ed948a51519c99e08cb9d88747a7565388306117' 
  AND token = 'IxKuEHV0UWjN5IgEjl54JP+tP/9d1gb9+yFAiL3yCpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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