SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6e3a309efce3dea32ba0e561531735ac801070b22da46473289a85358a28250' 
  AND token = 'ojZKReVR+NN57pSuGwQRPIUdJrKLoVwuK4RWIU3qrIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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