SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '579f02116dde1b8a55b5ce44489288a9788774ca6be916818dd18431a889f174' 
  AND token = '2CgLkHVqzmvyMSMTyOW71LqIW/wAgQIH+jAmB2Kc50E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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