SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0db3f73a40d450af462f10584dc3e73cee332aeb51606ae7bc8d1c96bf4f8a39' 
  AND token = '7kB1/1JZJcAuiR9NaAq8QiDujqotnzKuXp9SrISbkRw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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