SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '508b2ae2c30aaaf75da3f7c2371d811c15cc9ed1f5917ab1ad5748d5035f87be' 
  AND token = 'gRVs0hXNcXMrKfVZRMFb2FNtdvN7Ptt0whmao6mkW+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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