SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6829d41d9e01d03d00cc446fed96e16486f5c0f8e0299253cb70d014800a181' 
  AND token = 'NkV6/Fiq5568fSVAiczLxQxQgs3MXaS4zGPu5gvKv2w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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