SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4400240947fabfba17e6f9e4988ab1cb47001e94b9ecdb4e70b19386331a2aff' 
  AND token = '81z9SHp2fPGd8ZQI+d+Slk7XV7GSAIFjQfv23HihwPY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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