SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'feb3d8295c12d1693c4d9725558179cb738574d5f4988d301a95876a5d676c55' 
  AND token = 'oS/8DwqZxt0vapVQ99KavuJTw+pvDK2StWp8xd0WQMI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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