SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6751ac458f5aebf166abaede9a944eb60c4c39b9a6d37693936ff5eae7800bb1' 
  AND token = 'URb00EUp1BtVpxqYTMtDTZkiNEf4+mNHvzbZAU0sYXM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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