SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '623513541c27ecb487aee241a498a3409cd36673d798d49e5084a814c598f3a5' 
  AND token = '6DiNZrRttQAxsDqAgLDFFQHQs8fuVnM4yKYR68yjgp8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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