SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91ecbb03b0e23f39afbc2646454b206af8b66f7466744b16e10f6c62d25d5874' 
  AND token = '5SS8YZ011YqhT5k/rxAeKVt6/pEEh4KDuv94pzSruAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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