SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b49c0d807dc12a1d015325788c0d5d53d9fa2d1343ab80273838c4bb6c8df982' 
  AND token = 'AbG/K2clAsW+033D6kVhxzhef1J1fQzQ3hCfnW0qSHg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}