SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cb4773fb8566900ff5e9bd14ea0d865dc79282c55c4a03d6c6d983cea1da8b2' 
  AND token = 'btXqTxkAizVTI31hafXxcF66gMDdK1EV+MwXan2DBiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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