SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd98252ab29e43c0a4e7cb4fc78963bfdf098c3d901dc11cf2afd1b4d631a60ab' 
  AND token = 'R9oRQsU2161iFlzs1dKyIoa5ndB198Y4lKwxISNirPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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