SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bdfdbeedacabacb053cfcb862f4223794c68667b462642909caa24f76d5f476' 
  AND token = 'b7jdgARMD4BpwLDESbefNN8Y/VLHwJShxpEQI2tCKhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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