SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da541497487f5d9736059fe0aa174f285f3d3029d73233173a69112a49ba7222' 
  AND token = 'RuD9KgqmXJruyTjBYS2YT1b0AgtmFVBMekwZ5khzJo8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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