SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '730f9cb2f108c94f18114afd819ecaf04dd4c2885f42236409e4ce19561eb1b3' 
  AND token = '0cERpvxVfIbePPJ53EAczTZNbN4UKu+kNLMXNHLS6YI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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