SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7f430271d36e713051415a3f30af822d1b1b0b4fc079aac57402b21973554c5' 
  AND token = 'mWYhdpc9XtvlV+RMU/mtehv1goVSIwC1RP/iRb5VWCM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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