SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f4d30fe504fc7ac67c15c20ba09cb7ad230f05c4e68144970f8c8f16c3e5eb7' 
  AND token = 'YkMXXRnqBVlMXmy2FLKZGAxLQiTSw6EhlqFnYpk3ACk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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