SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21ead260e0775695eecc1b7477448526cdb2eff3525cd1076b55fcb315066cbc' 
  AND token = 'HAnKk8T5+ydQHzPu5KQein+cl6YO+9HJ5cGofMDiQew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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