SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '393e43055d97e201507520fc7ad65d5e6a8625e6e474b3de363eba65f57c5e1c' 
  AND token = 'k87KeASCB1dvLPFUZzyrZe4P7zIcZHZNYQ4sQ9vTJX8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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