SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e8cba830f73e65a0b230df092cb1c2bd5e8bbcb34aef0b0f8f43448dd41f592' 
  AND token = 'Xw+qlcw9c7PtpNn2Hf5oh5fX8z/HqBXfEmtswQUYZY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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