SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8312abfe134d0dc9ba9a2042a53dea6e3f22d82abee6146e977d7dffd9f37d88' 
  AND token = 'mxbWUC5TOSWe2zJrivzJjXMVPqyCr0uBKiPgFRvuJQk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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