SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9689249cc37080532dc6e8352c45926576b6e9557d24368bcb04453d702b1eb1' 
  AND token = 'e1DNJOniR0mTNfKxAhKG9tTchsA/sVqLQk/IMDSkcJU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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