SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a0016a443bc753013cfdcecfa66145bbe3fdba8fe81f08bfd842086db334cc2' 
  AND token = 'aUb2ttzLL/5h18hu8xdD0IP19bN4i/wDW4JCBhw793s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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