SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b0ecdc762c075a27332c09196d5263d206e538adec709c149e6e35890d17698' 
  AND token = 'LEhjQWL9YWTHtZ0FMpg5IxPVxJsiYedVvtV2TBLadzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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