SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74e6951575978c281f8d9465f793f181edde026b0e860997416b48dcefe218f6' 
  AND token = '3t4sXkRwpjqgsxfPD07Lp1ReuSoLQa/HtUxF4/Iiar0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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