SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5bd91391eef07b0689bb82ceea28d83ab43c64e7d2a30e3e025aa2d49b9fcb68' 
  AND token = 'F4lJQ4U11rpt/EyBGgy+wl7LVItv04QUvJ+sRzIafhY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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