SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b085e509bf69cbe7916ffef039d6599a568e26e7a0a5a2d33325a07b9001e5bc' 
  AND token = 'gDFo9+o5aI3hHtt8h6unEGq1eD3nb7UKxLjyU+F+JvI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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