SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a82b7402bc48e94b1aa2af962dfb0b7c06fdce761a91243ae07395e4e61abb8' 
  AND token = 'fuTqZW705bjLQDtTVQz5YQzFcM/+aNxtXQKcZIglQJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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