SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3041ff5111f31930c1001d58855eb1c5dead89df7e684980caa088c95044f50c' 
  AND token = 'ewZAcULFrR16hhlDTwFH1/LXw7oExE0A4kKulMruxL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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