SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb8b3271465b5454647a4c98d7bea6e3ab0276e20f64e03e3d94f378af9e7fcd' 
  AND token = 'NWUn9rHBhBuGrtKP8hF7CDRSdjYCx2jjOPRTwgVUKms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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