SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da87cad14ca231d3c1ad09e7b8d77506d0f921a92168f32ad68f640fe9ad2c35' 
  AND token = 'freg4kSr+VO1eZ/65LT6LhadZdWoh73ZsDiPYBMBA1g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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