SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef8c642b38b93951312315dcb467f3e064d05154ac601f351b1563a9f71e14c1' 
  AND token = 'mNJrrIPf9V7fig6D502XW+PLop8WdzRWMk3CQpqkgTo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}