SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31dba261f72081752bcce958a806c9d780da02c6f4f16095721b8fe36fb533c1' 
  AND token = '57QP7FPXimyMSsy11DqlWNMpS2QbAiWIM1f7hTMXDNw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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