SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8369b3f8f02af3df5ed9e9812aefe7017b43da22900add55fa48444a2591dee6' 
  AND token = '9xHsJc8FYTgHYUBjFbS4Wyx00mM7Xr9H2sXRVryCKhg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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