SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f197a1896b461a16d37e058089cecdc20f965a03a2f401773efffd018d838303' 
  AND token = 'YkEGY7K0bxon56G1PwPpx4oqQPPPHqLtXzVNoY1GYPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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