SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '298943b93c687d084afeb50968681a2e9edd2ff33a97855d223149bb2b66edb2' 
  AND token = 'M3caIvFtx+goAQkNiW9VQGMSo03QMXmZCMPpJ5ALag8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}