SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31b3aa277c744cf93e010300b65d80fe81e36983a95eba773f4b643b5957a1cf' 
  AND token = '2YwcrEsTJExa4DqOlzIZCFUJVBvmqRGLSgEY3nxwPIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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