SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ab3dbef9b72ac405953c166710902e49fce938e3daa4e88cd8acd723e91c3ae' 
  AND token = '5p7K6QabrH5CtngbODVei4ePWstDBaR3NqFSHCSYT4c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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