SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd34813bf6acc5ae1e5d52f1053660af101191aaa6a076c9252652b85fa3c4b69' 
  AND token = '9ZuEM7LlOy5CXQ4qXloFyv5XkadeB/hF2QAU1+ZOQQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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