SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a84beeb774e5de27b9b8d781e639d9b2260625d0a732b9352e2a113ac6480bb' 
  AND token = 'MrH4JyAym8LnOGslBhxFRVxAAfCcjUqF+mYSPEGCgxc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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