SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '966aa8ed9f6264c9ee6ce0ed1e62548f2d939c3da8af294b438c1eb08d7d9ac8' 
  AND token = '7CsFaeQxeJT/dcl87m141oXB2NPhezdeBu/rUwzhQJw=' 
  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"
    }
  }
}