SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64a776ca3e8984b091421a1597708728670d2ab6a73dbe26d70c001a4b096be6' 
  AND token = '4KULOb+GEKRUfdFMBuKk25bKWduHsYAZwTMu2QskoIE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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