SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50eea1952d5bec22dc4746042842150249680ae7d098f90d5cfcd551e0b5e6d5' 
  AND token = 'YkvBccR7ovfdRli4yZvbk3+SSo26KcuWQ+NVQsOn1pA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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