SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b83f02590039ecff1878f8bc0afb8f3194996074a3ac91e36aa29ed8574172a' 
  AND token = 'vawm3tiNlcRwkdnzCZfK77jNVs3umE+0i3mntjymtSc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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