SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fccc8ff2d83d28115f001a43831bd81cc2244e3ee19dac18aa381b659ec5b8ce' 
  AND token = 'Rs3td/NhvKGvk9Nz/XS9WygqvGfqHfHBEB0/IRVsBw0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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