SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17a9175744bff6c434221440e1153768267fdd47c8b4fc8f24d1080fa69d525d' 
  AND token = 'e/9XJqhuNbwf1CUA0uzC5MGvwnzGJfCmXLQVR1t3rtk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}