SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd8f8f0e4b5d969178fd0d36da6d6ab3c65988d85ec400e1a85a18292f315996' 
  AND token = 'qKvYYJ9FZ+GeVOUdCpVxfvlZtXXK/oDFZ3tgKGPOP0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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