SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be0a829f4a64f8be44665c17e2086aa1264319a66e68a9aa8d6d5f1bc2254850' 
  AND token = 'nblM4LYYnxvlLlON3HWGFmDUf4kStlWLDy5SkKAQHLQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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