SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4042331268f697baf1ced081baf91e0b40ff92d2baffe40dfaaab17783a233a2' 
  AND token = 'x5LKdqROIYvGk0rWhAgv89QqEsH9vK7af7feI+PmcVw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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