SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e9fdcaf893e5eda9fe575f997a587d188ed4f6df731a21ddc87723d302562c8' 
  AND token = '9Zp7mgRCYUuKQA5ArGiAGUzEMgJpwCSQgVN5ZMHEK7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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