SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4bb412c56bc22837611cd1a292c53021021b66b4f5c484add105babf94fab8f9' 
  AND token = 'wixAVxs7LRQLjgJWbEmNtR8VmdBjrd0ZCZNDYXkFPyo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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