SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '09839b7961b670e6aea19fcd58bc073314af6043b93d4f7d83d83266bfd8dd66' 
  AND token = 'H+JjfB+Y9eurKwNDrTMEYETu+5Akrt/0rz0YECDtwn8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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